INFO: rcu detected stall in br_handle_frame

Status: upstream: reported C repro on 2024/02/08 13:52
Reported-by: syzbot+e89f73a86247175d216a@syzkaller.appspotmail.com
First crash: 911d, last: 261d
▶ ▼ Bug presence (1)
Date Name Commit Repro Result
2026/07/21 upstream (ToT) b95f03f04d47 syz Failed due to an error; will retry later
▶ ▼ Similar bugs (16)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in br_handle_frame (5) bridge 1 syz 24 636d 665d 28/29 fixed on 2024/11/12 23:31
linux-4.14 INFO: rcu detected stall in br_handle_frame (3) 1 1 2138d 2138d 0/1 auto-closed as invalid on 2021/01/28 07:46
upstream INFO: rcu detected stall in br_handle_frame 1 syz, C done 341 2518d 2523d 13/29 fixed on 2019/10/09 10:54
upstream INFO: rcu detected stall in br_handle_frame (2) net 1 syz, C done 2 2422d 2418d 15/29 fixed on 2020/02/18 14:31
upstream INFO: rcu detected stall in br_handle_frame (3) bridge 1 1 1847d 1847d 0/29 auto-closed as invalid on 2021/10/15 13:41
linux-4.14 INFO: rcu detected stall in br_handle_frame (2) 1 syz, C done 1 2423d 2423d 1/1 fixed on 2020/01/19 15:05
linux-4.14 INFO: rcu detected stall in br_handle_frame 1 syz, C done 15 2515d 2527d 1/1 fixed on 2019/12/07 19:24
linux-4.19 INFO: rcu detected stall in br_handle_frame (2) 1 syz, C error 31 1282d 2123d 0/1 upstream: reported C repro on 2020/10/14 18:56
linux-4.19 INFO: rcu detected stall in br_handle_frame 1 syz, C done 41 2515d 2527d 1/1 fixed on 2019/12/07 19:18
linux-6.1 INFO: rcu detected stall in br_handle_frame (2) 1 5 119d 305d 0/3 auto-obsoleted due to no activity on 2026/07/20 06:55
upstream INFO: rcu detected stall in br_handle_frame (6) prio:normal netfilter bridge 1 syz, C error error 163 11h45m 206d 0/29 upstream: reported C repro on 2026/01/13 18:06
linux-6.1 INFO: rcu detected stall in br_handle_frame 1 2 711d 793d 0/3 auto-obsoleted due to no activity on 2024/12/04 21:21
upstream INFO: rcu detected stall in br_handle_frame (4) kernel 1 1 1686d 1686d 0/29 closed as invalid on 2022/02/08 10:10
linux-6.6 INFO: rcu detected stall in br_handle_frame 1 21 30d 260d 0/2 upstream: reported on 2025/11/21 04:49
android-5-15 BUG: soft lockup in br_handle_frame 1 2 720d 725d 0/2 auto-obsoleted due to no activity on 2024/11/16 05:31
linux-4.14 BUG: soft lockup in br_handle_frame 1 3 2522d 2525d 0/1 auto-closed as invalid on 2020/01/09 20:54
▶ ▼ Last patch testing requests (2)
Created Duration User Patch Repo Result
2026/07/06 14:07 19m retest repro linux-5.15.y report log
2026/04/25 02:24 23m retest repro linux-5.15.y report log
▶ ▼ Fix bisection attempts (8)
Created Duration User Patch Repo Result
2025/01/07 02:57 2h34m fix candidate upstream OK (0) job log
2024/11/28 23:08 18m fix candidate upstream error job log
2024/10/15 04:51 0m fix candidate upstream error job log
2024/07/30 22:36 17m fix candidate upstream error job log
2024/06/07 09:56 17m fix candidate upstream error job log
2024/04/22 07:33 18m fix candidate upstream error job log
2024/03/16 09:58 17m fix candidate upstream error job log
2024/02/14 20:51 17m fix candidate upstream error job log

Sample crash report:
watchdog: BUG: soft lockup - CPU#1 stuck for 24s! [kworker/1:11:4172]
Modules linked in:
irq event stamp: 48017
hardirqs last  enabled at (48016): [<ffff80000ffb4e10>] process_backlog+0x6d4/0x7e0 net/core/dev.c:6541
hardirqs last disabled at (48017): [<ffff800011b52e8c>] enter_el1_irq_or_nmi+0x10/0x1c arch/arm64/kernel/entry-common.c:227
softirqs last  enabled at (48010): [<ffff800010a62aec>] local_bh_enable+0x10/0x34 include/linux/bottom_half.h:31
softirqs last disabled at (48011): [<ffff8000081b847c>] __do_softirq kernel/softirq.c:592 [inline]
softirqs last disabled at (48011): [<ffff8000081b847c>] do_softirq_own_stack include/asm-generic/softirq_stack.h:10 [inline]
softirqs last disabled at (48011): [<ffff8000081b847c>] do_softirq+0xfc/0x1b0 kernel/softirq.c:459
CPU: 1 PID: 4172 Comm: kworker/1:11 Not tainted 5.15.180-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: ipv6_addrconf addrconf_dad_work
pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : arch_local_irq_restore+0x8/0x10 arch/arm64/include/asm/irqflags.h:131
lr : lock_is_held_type+0x150/0x1a8 kernel/locking/lockdep.c:5668
sp : ffff800020716600
x29: ffff800020716600 x28: ffff0000cb7bbb40 x27: ffff800020716720
x26: ffff0000c167b680 x25: ffff800014ac3d00 x24: ffff800014c11c20
x23: 0000000000000003 x22: ffff0000c167c0d8 x21: ffff800014d41be0
x20: 0000000000000001 x19: 0000000000000000 x18: 0000000000000101
x17: 0000000000000000 x16: ffff8000082ed688 x15: 0000000000000002
x14: ffff0000c167b680 x13: 0000000000ff0100 x12: 0000000000000006
x11: 0000000000000101 x10: 0000000000000003 x9 : 0000000000000000
x8 : 00000000000000c0 x7 : 0000000000000000 x6 : ffff800010c8bd5c
x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000000001
x2 : ffff0000cb7bbb40 x1 : ffff800011cacea0 x0 : 0000000000000000
Call trace:
 arch_local_irq_restore+0x8/0x10 arch/arm64/include/asm/irqflags.h:122
 lock_is_held include/linux/lockdep.h:287 [inline]
 rcu_read_lock_held+0x34/0x50 kernel/rcu/update.c:311
 br_port_get_rcu net/bridge/br_private.h:415 [inline]
 br_handle_frame_finish+0x108/0x1264 net/bridge/br_input.c:78
 br_nf_hook_thresh+0x388/0x47c net/bridge/br_netfilter_hooks.c:-1
 br_nf_pre_routing_finish_ipv6+0x828/0xaf4 net/bridge/br_netfilter_ipv6.c:-1
 NF_HOOK include/linux/netfilter.h:302 [inline]
 br_nf_pre_routing_ipv6+0x2ac/0x628 net/bridge/br_netfilter_ipv6.c:237
 br_nf_pre_routing+0x548/0x102c net/bridge/br_netfilter_hooks.c:512
 nf_hook_entry_hookfn include/linux/netfilter.h:142 [inline]
 nf_hook_bridge_pre net/bridge/br_input.c:242 [inline]
 br_handle_frame+0x870/0xf04 net/bridge/br_input.c:384
 __netif_receive_skb_core+0xf10/0x3420 net/core/dev.c:5418
 __netif_receive_skb_one_core net/core/dev.c:5522 [inline]
 __netif_receive_skb+0x114/0x400 net/core/dev.c:5638
 process_backlog+0x3ec/0x7e0 net/core/dev.c:6515
 __napi_poll+0xb4/0x624 net/core/dev.c:7074
 napi_poll net/core/dev.c:7141 [inline]
 net_rx_action+0x500/0xc10 net/core/dev.c:7231
 handle_softirqs+0x384/0xdbc kernel/softirq.c:558
 __do_softirq kernel/softirq.c:592 [inline]
 do_softirq_own_stack include/asm-generic/softirq_stack.h:10 [inline]
 do_softirq+0xfc/0x1b0 kernel/softirq.c:459
 __local_bh_enable_ip+0x298/0x470 kernel/softirq.c:383
 local_bh_enable+0x28/0x34 include/linux/bottom_half.h:32
 rcu_read_unlock_bh include/linux/rcupdate.h:809 [inline]
 ip6_finish_output2+0x1400/0x1cec net/ipv6/ip6_output.c:131
 __ip6_finish_output+0x580/0x6ec net/ipv6/ip6_output.c:201
 ip6_finish_output+0x40/0x218 net/ipv6/ip6_output.c:211
 NF_HOOK_COND include/linux/netfilter.h:291 [inline]
 ip6_output+0x274/0x594 net/ipv6/ip6_output.c:234
 dst_output include/net/dst.h:452 [inline]
 NF_HOOK include/linux/netfilter.h:302 [inline]
 ndisc_send_skb+0xc94/0x18a8 net/ipv6/ndisc.c:513
 ndisc_send_rs+0x49c/0x604 net/ipv6/ndisc.c:707
 addrconf_dad_completed+0x5f8/0xb70 net/ipv6/addrconf.c:4278
 addrconf_dad_work+0xa6c/0x12f4 net/ipv6/addrconf.c:-1
 process_one_work+0x790/0x11b8 kernel/workqueue.c:2310
 worker_thread+0x910/0x1034 kernel/workqueue.c:2457
 kthread+0x37c/0x45c kernel/kthread.c:334
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:870

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/04/17 20:10 linux-5.15.y f7347f400572 229db4cf .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 BUG: soft lockup in br_handle_frame
2025/11/19 22:57 linux-5.15.y cc5ec8769306 26ee5237 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in br_handle_frame
2024/02/08 13:52 linux-5.15.y 6139f2a02fe0 6404acf9 .config console log report syz C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in br_handle_frame
* Struck through repros no longer work on HEAD.